1. Field of the Invention
This invention relates to the field of data processing systems. More particularly, this invention relates to the field of the control of data processing performance, such as, for example, so as to reduce the energy consumed by a data processing system.
2. Description of the Prior Art
An important consideration in data processing systems is their energy consumption. Data processing systems which consume less energy allow longer battery life in mobile devices, tend to run cooler and more reliably, and require fewer special engineering considerations to deal with heat dissipation and the like. It is strongly desirable to reduce the energy consumption of data processing systems.
Balanced against a desire to reduce the energy consumption of data processing systems is a simultaneous desire to increase their performance level to deal with increasingly computationally intensive tasks. Such tasks often require highly intensive processing operations for short periods of time followed by relatively long idle times in which little computation is required.
In order to address the above two factors, it is known to produce data processing systems that are able to change their performance level so that high computational performance is provided in some configurations and low energy consumptions in other configurations. Known systems, such as the LongRun software produced by Transmeta, or the SpeedStep systems produced by Intel, allow a processor to be switched between such different configurations. In order to match the desired performance goals, a high computational performance configuration would be one with a relatively high operating voltage and a relatively high processor clock frequency. Conversely, a low energy consumption configuration has a relatively low operating voltage and a relatively low processor clock frequency.
As well as providing the performance and energy management capabilities described above, another important design characteristic is that hardware and software designs should be re-useable in a relatively large number of different circumstances. If computer software, such as operating system software, has to be re-written for different hardware implementations, or the hardware designs significantly modified for different hardware implementations, then this is strongly disadvantageous.